Video: Multiplying Two-Digits Numbers

A jaguar sleeps for about 77 hours in a week. How many hours of sleep would a jaguar get in 12 weeks?

02:12

Video Transcript

A jaguar sleeps for about 77 hours in a week. How many hours of sleep would a jaguar get in 12 weeks?

The first piece of information that we’re given in this problem is that we’re told that the jaguar sleeps for about 77 hours in a week. We need to use this fact to help us find out the number of hours of sleep a jaguar would get in 12 weeks.

Now, one way to find this answer could be to add 77 12 times. But a much quicker strategy would be to multiply 77 by 12. How can we make this multiplication easier? Well, we can start by partitioning 12. Let’s split it up into 10 and two. So, if we find the answer to 77 multiplied by 10 and then 77 doubled and we add the two together, we’ll find the answer to 77 times 12.

Firstly, let’s multiply by 10. When we multiply any number by 10, the digits move one place to the left. So, 77 becomes 770. Now, let’s find the answer to 77 multiplied by two. Two lots of 70 equals 140. And two lots of seven, we know is 14. Now, if we add 140 and 14 together, we get 154.

Now, if we add these two parts together, we can find the answer to 77 multiplied by 12. Zero plus four equals four. Seven plus five equals 12. And finally, in the hundreds column, seven plus one plus the one we’ve exchanged equals nine. And so, we can see the answer. If a jaguar sleeps for about 77 hours in a week, in 12 weeks a jaguar will sleep 924 hours.

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